Nerve blocks are known in the art and relate generally to the injection of local anesthetic proximal to one or more specific nerves to provide (usually) anesthesia or temporary control of pain. The anesthetic typically comprises a liquid that the service provider administers via a needle. Such a needle must be properly placed. Administering the anesthetic too far from the nerve can defeat the intended purpose, while contacting or inserting the needle into the nerve or its fascicles can cause nerve injury and harm to the patient.
Many service providers use ultrasonography to help guide the needle to a proper location. Unfortunately, while ultrasonography can help to avoid having the needle too distant from the nerve or impinging directly upon the nerve, ultrasonography cannot in and of itself guarantee a correct and risk-free placement of the needle. For example, ultrasonography alone cannot always guarantee that the needle tip is not disposed within a nerve, nerve fascicles, tendon, or other poorly-compliant spaces.
Accordingly, those skilled in the art often rely upon “feel” of the resistance to injection to help inform the correct placement of the needle during an injection of the medication (typically a local anesthetic solution). In particular, in many cases the abnormally high pressure within a needle incorrectly located in a poorly-compliant tissue informs this hand or syringe “feel.” A failure to “feel” an abnormally high resistance or a failure to abort the injection when such high resistance is “felt” can lead to an unrecognized injection into a wrong tissue. In turn, such an injection can result in a failure to accomplish a block or mechanical and injection damage to the injected tissues. Possibly adversely affected tissues and consequences include nerves (nerve damage), tendons (rupture and inefficient block) and blocking the wrong side of the tissue fascia (block failure).
Mechanical pressure monitors are also known in the art that can provide a general visual indication as to whether the current pressure in the needle is generally within a useful nominal range, below that useful nominal range, or above that useful nominal range.
Again, however, existing approaches in these regards are not sufficient to meet all user needs in all application settings.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.